Method of making hydrocyanic acid.



UNITED STATES PATENT OFFICE.

EMIL BERINGER, OF OHARLOTTENBURG, GERMANY.

METHOD OF MAKING HYDROCYANIC ACID.

SPECIFICATION forming part of Letters Patent N 0. 652,741, dated July 3,1900.

' Application filed October 4, 1899. Serial No. 732,544. (No specimens.)

To all whom, it ntcty concern:

Be it known that I, EMIL BERINGER, a subject of the King of Prussia,Emperor of Germany,residin g at Oharlottenburg, in the Kingdom ofPrussia, Germany, have invented certain new and useful Improvements inthe Processes of Producing Hydrocyanic Acid from Sultocyanides, of whichthe following is a specification.

The known oxidizing action of nitric acid on sulphocyanide, producinghydrogen cyanide, may be expressed by the equation:

-Various attempts have been made to render this reaction practicallyuseful; but all the processes devised suffer from the objection that inthe course of the reaction much of the hydrogen cyanide is oxidized tocarbon dioxide, so that the yieldof hydrogen cyanide is too small forprofitable application of the process.

I have found that the production of carbon dioxide in the process is dueto the action of free mineral acid, which in the case of the reactionexpressed by the above equation is sulphuric acid formed by the chemicalchange. It, therefore, this production of carbon dioxide is to besuppressed the reaction must be carried out in such manner that no freeacid is formed or can become active, and it is to such manner ofcarrying out the process that my invention relates.

For the purpose of avoiding the formation of free sulphuric acid Isubstitute for the nitric acid requisite for the oxidation an equivalentquantity of a nitratesuch as barium nitrate, calcium nitrate, or thelike. It now an acid capable of liberating nitric acid be allowed to actupon this nitrate, the nitric acid thus set free will oxidize some ofthe sulphocyanide, producing free sulphuric acid. The latter, however,will react with the nitrate present to form a sulphate and to liberatemore nitric acid, which in its turn oxidizes sulphocyanide. In thismanner the sulphocyanide may be oxidized without formation of free acid,as is expressed by the following equation, in which the barium salts areused as typical of suitable salts:

The production of carbon dioxide is reduced to a minimum when theoxidation of a sulphocyanide is efiected in this manner, and as aconsequence the yield of hydrogen cyanide is nearly that indicated bytheory.

The following example serves to illustrate the process: Eighty-two kilosof barium nitrate are dissolved in seven hundred liters of watercontained in a retort provided with a stirrer. Into the boiling hotsolution are poured either separately, in small portions, or mixedtogether and gradually a solution of 37.2 kilos of barium sulphocyanidein one hundred liters of water and a solution of 31.6 kilos of sulphuricacid of specific gravity 1.84 in one hundred liters of water. If bariumsulphocyanide or calcium sulphocyanide is used, it is advantageous tomix the solution of this salt with that of the sulphuric acid and toallow the barium sulphate or calcium sulphate to settle before pouringthe liquid into the barium-nitrate solution. The hydrogen cyanideliberated by the reaction distils over with the steam and is worked upin the usual manner.

I claim The herein-described process of producing hydrocyanic acidconsisting in slowly adding to a boiling aqueous nitrate solution, asolution of sulphocyanide together with a minwitnesses.

. EMIL BERINGER.

Witnesses:

WOLDEMAR I-IAUPT, HENRY I-IAsPER.

